Kenwood NXR-800 Service Manual page 12

NXR-800
2-8. AVR circuit
IC104, IC603, IC704, IC705, IC706, IC807, IC808 and
IC809 are AVR ICs.
Each circuit contains its own power regulator IC to main-
tain isolation between circuits.
2-9. Other circuits
In addition, IC701 is an EEPROM. The transmitter ad-
justment data adjusted for each unit is written into the
EEPROM. If the unit is installed in another set, it is not nec-
essary to adjust it again from the beginning, but only fi ne-
tuning is necessary for each unit.
3. Final unit
The RF final amplifier unit (X45-382 A/5) amplifies the
transmitter power to a specifi ed level.
This unit consists of the following circuits:
(1) Transmitter power module
(2) High pass fi lter
(3) Forward/Refl ect power detector circuit
(4) Antenna switch
(5) Harmonic fi lter circuit
(6) APC circuit
(7) High temperature detector circuit
(8) FAN action control circuit
(9) Current detector circuit
(10) AVR Circuit
(11) Other Circuits
12
CIRCUIT DESCRIPTION
CN801
VBATT IC704
+13.8V
IC809
IC104
IC808
Fig. 8 AVR circuit
The temperature sensor (IC804) monitors the tempera-
ture of the transmitter unit (X56-312 A/3).
The D/A converters (IC701 and IC802) converts the AGC
setting (D_PC) of the driver circuit and control voltage value
(PWR_CONT, PWR_PRT) of the Final Unit (X45-382 A/5).
The A/D converter (IC803) converts the transmitter unit
(X56-312 A/3) temperature, VCO & VCXO control voltage
(CVT, CVT-REF and CVT-MOD), Final Unit (X45-382 A/5) PA
current(PA_CURR), fan current (FAN_CURR), detection volt-
age (FWD_PWR, RFL_PWR), etc.
The shift register (IC703) controls each part of the trans-
mitter unit (X56-312 A/3) based on serial data of the Control
Unit (X53-413).
8V #2
CN807
8V
9V
Ripple
filter
8V #1
SW
IC807
IC706
IC705 IC603
3-1. Transmitter power module
The power module IC10 uses power module RA13H4452
M101 to improve its efficiency. The driver output of the
transmitter unit passes through an attenuator and enters the
power module IC10 pin 1. Power module IC10 amplifies
the RF power according to the voltage at the amplifi cation
control pin 2 (VGG) and outputs it through pin 4 (Pout).
RA13H4452M101
Pin
Fig. 9 Transmitter power module
3-2. High pass fi leter
The T type single stage high pass fi lter prevents the Pow-
er Amplifi er Module from being broken by static electricity.
8V #2
OCXO
9V'
8V #1
8V #1'
5V #1
5V #2
5V #3
3.3V
VGG VDD Pout